Fluid-actuated holding device for grinding machines



Dec. 8, 1964 H. E. BALSIGER 3,159,953

FLUID-ACTUATED HOLDING DEVICE FOR GRINDING MACHINES Filed March 1, 1962 4 Sheets-Sheet 1 FIG.

H. E. BALSIGER INVENTOR ATTORNEYS Dec. 8, 1964 H. E. BALSIGER 3,159,953

FLUID-ACTUATED HOLDING DEVICE FOR GRINDING MACHINES Filed March 1, 1962 4 Sheets-Sheet 2 H. E. BALSIGER INVENTOR B; M, mm W ATTORNEYS Dec. 8, 1964 H. E. BALSIGER FLUID-ACTUATED HOLDING DEVICE FOR GRINDING MACHINES Filed March 1, 1962 FIG. 4. z.

4 Sheets-Sheet 3 H. E. BALSIGER INVENTOR BY a, fail, M M

ATTORNEYS Dec. 8, 1964 H. E. BALSIGER 3,159,953

FLUID-ACTUATED HOLDING nzvzcm FOR GRINDING MACHINES Filed March 1, 1962 4 Sheets-Sheet 4 ATTORNEYS 3,159 953 FLUlD-ACTUATED ndrnnan nnvren non GRINDING MACS Harold E. Balsiger, Waynesboro, Pa., assignor to Landis Tool (Iompany, Waynesboro, Pa., a corporation of Pennsylvania Filed Mar. 1, 1962, Ser. No. 176,682

8 Ciairns. (Cl. 51-237) This application is a continuation-in-part of the application filed September 15, 1959, Serial Number 761,120 and now abandoned.

The following is a detailed specification of an invention in a fluid-actuated work clamping device for grinding machines. Ring-like workpieces, for example, the inner races of ball or roller bearings and the like, are customarily ground on the outer periphery or raceway by a concentric grinding machine. The workpieces are presented to a rotary chuck or headstock face plate by a loading arm and held in offset radial relation to the chuck axis by peripherally spaced work supporting shoes engaging the surface to be ground or another peripheral surface of the workpiece. The chuck is usually magnetic. The shoes serve to hold the workpiece in a radial position against the grinding wheel as the latter is advanced during a grinding operation. Grinding machines having these features are disclosed in Balsiger Patents 2,694,883, granted November 23, 1954, and 2,874,518, granted February 24, 1959.

In the case of miniature bearing rings, the surface of the workpiece which is in engagement with the chuck is so small that the magnetic force acting to hold the workpiece in place is inadequate to hold and control rotation of the workpiece under the grinding actionof the grind ing wheel, and in some cases, the workpiece is so small that a proper non-magnetic gap between the supporting pole pieces is too large in relation to the workpiece to properly support it. In such a case, a non-magnetic chuck must be used. Non-magnetic chucks or face plates aroused also for non-magnetic workpieces. In both cases, other means must be provided to hold the workpiece in driving relation with the face plate or driving member.

It is, therefore, an object of the present invention to provide means separate from the headstock of a grinding machine for holding a workpiece firmly against a driving plate for rotational control by said driving plate.

Another object is to supplement the magnetic force by which the workpiece is held in contact with the face plate.

A further object is to hold the workpiece against a nonmagnetic face plate by pressure alone, particularly when the work is of non-magnetic material.

Still another object is to maintain full contact with the workpiece and constant pressure on it even when its position relative to the face plate is shifted radially as a result of the reduction in diameter caused by the progress of the grinding operation. In other words, as the outer surface of the workpiece is ground away, the work moves radially to maintain contact with the supporting shoes, and the holding member is free to move radially with the workpiece.

The above and other purposes of the invention will be readily understood from the following description of the preferred form which has been illustrated by way of example on the accompanying drawings in which:

FIGURE 1 is a longitudinal horizontal section of the improved locating arbor and mounting taken on the line 1-1 of FIGURE 2 showing the radial position of the work and holding member at the beginning of the grinding operation;

FIGURE 2 is a left end view of the same;

loading arm and the actuating means and V ,15 ,953 Patented Dec. 8, 1 964 FIGURE 3 is a close-up section showingthe radial position of the work and holding member at the end of the grinding operation; v FIGURE 4 is, an elevation, partly in section of the FIGURE 5 is an hydraulic and electric diagram.

The general purpose of the invention is to provide pressure holding means associated with the loading arm of a grinding machine to receive an annular workpiece and transfer it to the face plate to hold the work against I said face plate for rotation with the face plate.

At the conclusion of the grinding operation, the hold-. ing member releases the workpiece and the arm swings said workpiece away from the face plate to an unloading position.

As illustrating the preferred form of the invention, I

have shown a magnetic chuck having a face plate or driving plate 8 forming part of headstock 6.

Housing 9 has means for pen'pherially supporting a workpiece for rotation. Also, it has means to hold said workpiece against driving plate 8. Housing 9 is firmly clamped in loading arm 10. Arm 10 is pivotally mounted for rocking movement into axial position relative to driving plate 8 for a grinding operation and in the opposite direction for the purpose of discharging the finished workpiece and reloading. Housing 9 is fastened axially in the arm 10 by means of nut 11. Housing 9 has an axial'bore 12 running from the front to the rear through which fluid under pressure is supplied. At the tear, it is connected to a fluid pressure manifold 13 by means of ports 14, 14. Manifold 13 is held on the rear end of housing 9. It has a passageway connecting ports 14, 14, but is held in a fluid-tight manner on the end of housing 9. The forward end of bore 12 is enlarged. to form a cylindrical chamber 15 which is centrally disposed in housing 9. The workpiece is shown here as an inner raceway 16 for a ball bearing. It is to be held in position eccentn} cally of driving plate 8 and against the periphery of grinding wheel 17 by means of peripherally spaced work=en gaging shoes 19 and 20. Support members 18 and 21 for the shoes may be attached to the housing or they may be mounted on the machine independently of the loading device. In either case, they are positioned to support the workpiece with its axis in offset relation to the axis of the face plate so that rotationof the face plate serves to hold the workpiece in firm contact with the supporting members 18 and 21.

Chamber 15 constitutes a cylindrical recess in which member 22 is freely movable. Member 22 has a rear end 23 which is tapered conically to conform to. the tapered part of the recess. between bore 12 and chamber Tapered end 23 has a large diameter flange portion 24 which restricts the flow of air from'bore 12 so that the resulting pressure urges member 22 axially to hold workpiece 16 against drivingplate 8.

Outflow of air is restricted and a force is exerted to shift-member 22 to the left to holdworkpiece 16 against driving plate 8. The axial movement of member 22 is confined in working range by its flange 27 and fixed ring 28.

Ring 28 is set in housing 9 in spaced relation to said flange 27 to form a groove 25 and to serve as a stop to the forward movement of flange 27 and member22. The diameter of flange 27 is less than the diameter of groove 25 by an amount suflicient to permit member 22 to move radially as a unit with the workpiece.

A work-engaging clamping member 29 is provided on the end of member 22.

An annular portion 31 having a recess 32 extends forwardly from clamping member 29 to receive the workpiece 16 and carry it to 7 passes centrally through clamping member 29 and is grinding position. Screw 33 threaded into boss 30 of member 22.;

- The clamping member 29 in FIG. 1 has a work engaging surface 34.. In the preferred form of the device shown in FIG. 3, work engaging surface 34 engagesthe flatend co-axial relation with workpiece 16 as said workpiece member 29. or its equivalent will hold a workpiece against face plate. 8 without the supporting function of portion While loading arm- 10 is in its retracted or loading position radially spaced from driving plate 8, workpiece 16 is received upon shoes 19and 20. During this time, member 22 in chamber 'is not under fluid pressure. Arm 10 is rocked into axial position opposite driving plate 8 with housing 9 holding workpiece 16 inplace opposite driving plate 8. Driving plate 8, if magnetic, will hold the side edge of workpiece 16and deposit it in constrained location on shoes 19 and 20 respectively to rotate with driving plate 8. Workpiece 16 will be supported from below and on therear by means of the shoes 19 and 20, respectively. e

To supplement the hold which the magnetic driving plate 8 has on workpiece 16, compressed air or another fluid under pressure is applied (against member 22. The fluid flows through the annular restriction formed between the flange 27-. Thus restricting the flow of the force created by the fluid serves to press member 29. against workpiece 16 and driving plate 8. In this arrangement of parts, member 22 is designed for minimum weight and is free of frictional resistance to rotation by being held against workpiece 16 and out of contact with the walls 7 of chamber 15.

To permit radial movement of holding member 29,

1 there is clearance between flange 27 and the adjacent in- Operation Arm 10 is shown in solid lines in FIGURE 4 in unload position, and in broken lines in intermediate positionand in grinding position. Arm 10. is moved in a clockwise direction from unload to load to grinding position by means of piston 115 moving to the left and turning shaft 81 by means of pinion 106 in engagement with rack 107 which is the piston rod for piston 115. Means for initiairing the various movements of arm 10 are described in Patent 2,874,518.

When the arm movesfrom intermediate or loading to horizontal or grinding position, limit switch SLS actuated by cam .58 on shaft 81, completes a circuit to energize of this device is,

holding member 29 can move radially to maintain a fixed moves radially during the grinding operation.

At the end of a grinding operation, size control contact 3 is opened by a size or time control device (not shown), de-energizing valve solenoid 5 land directing fluid under pressure to retract feed piston 46 and grinding wheel 17.

, In retracted position of wheel 17, limit switch 4LS is opened to de-energize air valve solenoid 6 to cut oil the supply of air to holding member 29. At the same time, a suitable control, disclosed in Patent 2,874,518, directs fluid to shift piston "115 to the right to return arm 10 to unload position. I

' As described above, provision is made to receive a workpiece and present it to the face plate of :a headstock opposite a grinding wheel. The workpiece is supported in grinding position andheld by fluid pressure against the faceof the headstock. As grinding progresses, the pressure-operated holding means moves laterally as a unit with the workpiece to maintain adequate pressure on the workpiece at peripherally spaced points on the external surface being ground, so that the workpiece moves radially as it is ground to a smaller diameter, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance. between said holding member md said housing being equal to or greater than said radial movement of said workpiece, a supply-of fluid under pressure, means for directingsaid fluid under pressure against and around said holding member floating said holding member relative to said housing and holding said workpiece against said face plate, the front'portion of said holding member. moving radially in the housingand maintaining substantial coaxial relation with said workpiece. as it moves radially during a grinding operation. 1

2. A holding device for holding an annular workpiece for external grinding in a grinding machine comprising a rotatable face plate, means mounted independently of said face plate including a housing, means for moving said housing toward and from operative relation with said face plate, means for supporting said workpiece at peripherally spaced points on the external surface being ground so that the workpiece moves radially as it is ground to a smaller diameter, a holding member loosely mounted in said housing and rotatable withsaid workpiece, the clearance between said holding member and said housing being control relay 13CR. Relay contact 13CR1 completes a left hand position, valve 120 Idirects fluid under pressure to actuate member 22 to hold workpiece 16 against driving plate 8.

. As indicated above, workpiece .16 is supported on the surface being ground by peripherally spaced shoes 19 and 20. As the workpiece is ground to a smaller diameter, it move radially to maintain engagement with shoes 19 and20;

= Sufficient clearance is provided between groove, 25 in 9 and the flange of holding member 29 so that equal to or greater than said radial movement of said workpiece, a supply of fluid under pressure, means for directing said fluid under pressure against said holding member to hold said holding member and said workpiece against said face plate, the front portion of said holding member and said workpiece moving radially as a unit relative to said housing as said workpiece moves radially during a grinding operation.

3. A holding device for holding an annular workpiece for external grinding in a grinding machine comprising a rotatable face plate, a loading arm mounted independently of said face plate, a non-rotatable housing in said loading arm, means on said housing for supporting said workpiece at peripherally spaced points on the external surface being ground so that the workpiece moves radially as it is ground'to a smaller diameter, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance between said holding member and said housing being equal to or greater than said radial movement of said workpiece, a supply of fluid under pressure, means for directing said fluid under pressure against said holding member to hold said holding member and said workpiece against said face plate, the front portion of said holding member and said workpiece moving radially as a unit relative to said housing as said workpiece moves radially during a grinding operation.

4. A holding device for holding an annular workpiece for external grinding in a grinding machine comprising a rotatable face plate, a loading arm for presenting a workpiece in position to be rotated by said face plate for a grinding operation, a housing in said loading arm, said loading arm being movable from a work receiving position to a grinding position, means for supporting said workpiece on the external surface being ground, the workpiece moving radially relative to the face plate as it is ground to a smaller diameter to maintain contact with said supporting means, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance between said holding member and said housing corresponding to the radial movement of said workpiece, a supply of fluid under pressure, means operable in response to the movement of said loading arm to grinding position to direct fluid under pressure against said holding member to hold said workpiece against said face plate, the front portion of said holding member moving radially in said housing and maintaining a substantial coaxial relation with said workpiece as it moves radially during a grinding operation.

5. A holding device for holding an annular workpiece for external grinding in a grinding machine comprising a rotatable face plate, means mounted separately from said face plate including a housing, means for moving said housing between a loading position and a grinding position in operative relation with said face plate, means for supporting said workpiece on the housing at peripherally spaced points on the external surface being ground as a result of which a workpiece moves radially as it is ground to a smaller diameter, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance between the front portion of said holding member and said housing being suflicient to accommodate said radial movement of said workpiece, a supply of fluid under pressure, and means operable in response to movement of said housing to grinding position for directing said fluid under pressure against said holding member to hold said holding member and said workpiece against said face plate, the front portion of said holding member and said workpiece moving radially as a unit relative to said housing during a grinding operation.

6. In combination with a grinding machine having a rotatable face plate, a grinding wheel, and means for feeding said grinding wheel toward and from said face plate for a grinding operation; a movable loading arm for presenting a workpiece in position to be rotated on said face plate, said loading arm being movable from a Work-receiving position to a grinding position, a housing in said loading arm, means on the housing for supporting said workpiece on the external surface being ground, the workpiece moving radially relative to the face plate as it is means operable in response to the movement of said loading arm to grinding position to direct fluid under pressure against said holding member to hold said workpiece against said face plate, and to actuate said feeding means to advance said grinding wheel for a grinding operation, the front portion of said holding member freely moving radially in said housing to maintain a substantial coaxial relation with said workpiece as it moves radially during a grinding operation.

7. A rotatable face plate, means for supportingsaid workpiece at peripherally spaced points on the external surface being ground to permit the workpiece to move radially as it is ground to a smaller diameter, a housing separate from said face plate, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance between said holding member and said housing corresponding to said radial movement of said workpiece, a supply of fluid under pressure, means 7 8. A rotatable face plate, means for supporting said workpiece at peripherally spaced points on the external surface being ground to permit the workpiece to move radially as it is ground to a smaller diameter, a housing separate from said face plate, a holding member loosely mounted in said housing and rotatable with said workpiece, the clearance between said holding member and said housing corresponding to said radial movement of said workpiece, a supply of fluid under pressure, means for directing said fluid under pressure against said holding member to hold said holding member and said workpiece against said face plate, said holding member being supported radially solely by the means for supporting the workpiece on the surface being ground.

, References Cited inthe file of this patent UNITED STATES PATENTS 

2. A HOLDING DEVICE FOR HOLDING AN ANNULAR WORKPIECE FOR EXTERNAL GRINDING IN A GRINDING MACHINE COMPRISING A ROTATABLE FACE PLATE, MEANS MOUNTED INDEPENDENTLY OF SAID FACE PLATE INCLUDING A HOUSING, MEANS FOR MOVING SAID HOUSING TOWARD AND FROM OPERATIVE RELATION WITH SAID FACE PLATE, MEANS FOR SUPPORTING SAID WORKPIECE AT PERIPHERALLY SPACED POINTS ON THE EXTERNAL SURFACE BEING GROUND SO THAT THE WORKPIECE MOVES RADIALLY AS IT IS GROUND TO A SMALLER DIAMETER, A HOLDING MEMBER LOOSELY MOUNTED IN SAID HOUSING AND ROTATABLE WITH SAID WORKPIECE, THE CLEARANCE BETWEEN SAID HOLDING MEMBER AND SAID HOUSING BEING EQUAL TO OR GREATER THAN SAID RADIAL MOVEMENT OF SAID WORKPIECE, A SUPPLY OF FLUID UNDER PRESSURE, MEANS FOR DIRECTING SAID FLUID UNDER PRESSURE AGAINST SAID HOLDING MEMBER TO HOLD SAID HOLDING MEMBER AND SAID WORKPIECE AGAINST SAID FACE PLATE, THE FRONT PORTION OF SAID HOLDING MEMBER AND SAID WORKPIECE MOVING RADIALLY AS A UNIT RELATIVE TO SAID HOUSING AS SAID WORKPIECE MOVES RADIALLY DURING A GRINDING OPERATION. 